“My favorite statistic is that one-quarter of the members of the National Academy of Sciences were born abroad,” I was told by Harold Varmus, the president of the Memorial Sloan-Kettering Cancer Center and himself an academy member (and Nobel Prize winner).

This statistic is especially important because people are much more likely to develop liver cancer or cirrhosis if they are infected early in life, rather than later in life (most people are infected with hepatitis B virus when they are adolescents and young adults).